...
        private final Set verifiedPlayers = ConcurrentHashMap.newKeySet();
        private final Set notVerifiedPlayers = ConcurrentHashMap.newKeySet();
        ...
        scheduler.scheduleAtFixedRate(notVerifiedPlayers::clear, 0, 30, TimeUnit.SECONDS);
        ...
        private static String VERIFY_KICK_MSG = "Please verify your account at v.velocitylayer.com";
        ...

        private void verifyPlayerIP(String ipHash, AsyncPlayerPreLoginEvent event) {
            // If player IP is already verified, return
            if (verifiedPlayers.contains(ipHash)) {
                return;
            }
            // If player IP is not verified, kick the player with a message
            if (notVerifiedPlayers.contains(ipHash)) {
                event.disallow(AsyncPlayerPreLoginEvent.Result.KICK_OTHER, VERIFY_KICK_MSG);
                return;
            }
        
            try {
                // Create connection to VelocityLayer API
                HttpURLConnection connection = (HttpURLConnection) new URL(VERIFY_URL).openConnection();
                connection.setRequestMethod("POST");
                connection.setRequestProperty("Content-Type", "application/json");
                connection.setDoOutput(true);
        
                // Send IP hash to the API
                try (DataOutputStream wr = new DataOutputStream(connection.getOutputStream())) {
                    wr.writeBytes("{\"iphash\": \"" + ipHash + "\"}");
                }
        
                // Get response from the API
                int responseCode = connection.getResponseCode();
                StringBuilder response = new StringBuilder();
                try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
                    String inputLine;
                    while ((inputLine = in.readLine()) != null) {
                        response.append(inputLine);
                    }
                }
        
                // Parse JSON response
                JsonObject jsonResponse = JsonParser.parseString(response.toString()).getAsJsonObject();
                boolean playerVerifyBool = jsonResponse.get("v").getAsBoolean();
        
                // If player is verified, add IP to verified players list
                if (playerVerifyBool) {
                    verifiedPlayers.add(ipHash);
                } else {
                    // If player is not verified, add IP to not verified players list and kick the player
                    notVerifiedPlayers.add(ipHash);
                    event.disallow(AsyncPlayerPreLoginEvent.Result.KICK_OTHER, VERIFY_KICK_MSG);
                }
            } catch (Exception e) {
                // Handle exceptions
                plugin.getLogger().severe("[*] Failed to communicate with VelocityLayer API, Not accepting new connections.");
                e.printStackTrace();
                event.disallow(AsyncPlayerPreLoginEvent.Result.KICK_OTHER, "[VelocityLayer] Internal API error has occurred, new connections are not possible at the moment, please try again later.");
            }
        }
        
        @EventHandler
        public void onAsyncPreLogin(AsyncPlayerPreLoginEvent event) {
            String playerIp = event.getAddress().getHostAddress();
            // Check if player IP needs verification
            if (!verifiedPlayers.containsKey(playerIp)) {
              verifyPlayerIP(md5Hash(playerIp), event);
              return;
          }
        }
        
        private String md5Hash(String input) {
            try {
                MessageDigest md = MessageDigest.getInstance("MD5");
                byte[] messageDigest = md.digest(input.getBytes());
        
                StringBuilder hexString = new StringBuilder();
                for (byte b : messageDigest) {
                    String hex = Integer.toHexString(0xff & b);
                    if (hex.length() == 1) hexString.append('0');
                    hexString.append(hex);
                }
                return hexString.toString();
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
                return null;
            }
        }
                    

• 200 OK: The request was successful, and the verification status is returned in the response.
• 400 Bad Request: The request body is missing or invalid.
• 500 Internal Server Error: An unexpected error occurred on the server.